Reclosing circuit breaker



INVENTOR l/fief /14 //a//aaa Dn. m1 Emu. cl .au MT?. f LN2 n mw. r S 0 Mmm 24 6 s1 J 6 Mm.. 4 4o 2 e E R m 6 0 w, i n KJ 8 \C w sept. 16, 1952 ffy. J

WITNESSES: M

vopening characteristic similar to fuses.

Patented Sept. 16, 1952 RECLOSING CIRCUIT BREAKER James M. Wallace, East McKeespoi-t, Pa., as-

signor to Westinghouse Electric Corporatlon, East Pittsburgh, Pa., a corporation of Penn- Sylvania Application September 27, 1947, Serial No. 776,563

` (o1. 20o-e9) 5 Claims. i Y vl This invention relates to f. electric circuit breakers generally, and more particularly, to 0D- erating mechanism means governing circuit opening time characteristics or" a breaker.y

In providing protection for a circuit against overloads and short circuits, various type of circuit interrupting devices are commonly employed at different points along the circuit, and it is highly desirable that these devices be coordinated as to operation for the ultimate purpose of isolating the faulty section or branch of the circuit without substantially disturbing continuity oi service to the remainder of the circuit. Fuses are commonly used for the protection of certain apf paratus and for the protection of branch circuits in which such apparatus is located, and automatic reclosing circuit breakers are used ahead of such fuses in the circuit for the purpose o1" ultimately isolating the faulty part of the circuit by requiring operation of the fuse protecting that part of the circuit. Each circuit breaker may thus be used to protect a number of fuses which may vary in current rating, with the breaker designed to open and reclose the circuit a number of times.

ln order to properly coordinate with .fuses which have an inherent thermal inverse timecurrent characteristic, various time delay means such as dashpots, mechanical tickers, etc., have been employed to give circuit breakers a circuit Such devices enable a breaker to coordinate very Well with fuses on low currents, but on high currents the resistance of such time delay means apn proaches infinity at least for a short time, and consequently coordination with fuses becomes eX- tremely dilicult. 7

One object of this invention is to provide a circuit breaker of the type described with novel time delay means to cause the breaker to have a circuit opening time characteristic closely approximating that of a fuse.

Another object of this invention is to provide a circuit breaker of the type described having novel time delay means for delaying a circuit interrupting operation and wherein the resistance offered by the time delay means decreases for high current interrupting operations.

Still another object of thisinvention is to provide a circuit breaker of the type described having a dashpot for delaying a circuit opening means, with novel means for decreasing the effect of the dashpot on high current circuit interrupting operations. l y

Another object of this invention is lto provide a circuit breaker of the type described having an overload responsive member which is normally movable a predetermined distance before causing a circuit interruption with time delay means delaying movement of said member, and with novel means responsive to high overloads for causing a circuit opening operation in response to a lesser movement of said overload responsive member.

Another object of this invention is to provide novel hydraulic and mechanical operating means for a circuit breaker which is selective in operation dependent upon the magnitude of overload to be interrupted.

These and other objects of this invention will be more apparent upon consideration of the folu lowing description of preferred embodiments ci the invention, when taken in connection with the attached drawing, in which:

Figure l is a lschematic view oi a reclosing circuit breaker constructedin accordance with this invention, with parts of the breaker shown in section;

Fig. 2 is an enlarged partial sectional view through the breaker shown in Fig. 1;

Fig. 3 is also a partial sectional view similar to Fig. 2, but illustrating another embodiment oi this invention;

Fig. 4 is also a partial sectional view of a circuit breaker similar to Figs. 2 and 3 but illustrating still another modified form or the invention, and

Fig. 5 is a chart illustrating time-current curves of fuses and circuit breakers.

The automatic reclosing circuit breaker diagrammatically illustrated in Fig. 1 of the drawing has a stationary contact 2 and a movable contact 4 mounted on the lower end of a movable contact rod 35. The upper end of contact rod 36 is pivoted'as at 1 to a lever 8 which is pivoted as at i2 on a bracket I3 secured to the cover i4 of a casing l5 for the breaker. Lever 8 is biased in a clock wise direction by a coil tension spring i6 connectedbetween a pin Zil on lever 8, and a pin it on bracket I3. f

In order to separate movable contact f1 from stationary contact' 2,'a'solenoid coil which is annular in form is provided about contact rod' and is supported between spaced supporting i 24 which may be stationariiy mounted in casing in any desired manner. Insulation "it, which may be of fiber or of a molded insulating materia-i, is provided for lining the interior of solenoid coil 2:2, and preferably extending over the ends of the coil between the coil and stationary supporting plates f `24. A hollow cupshaped core 23 is adapted to end of the coil 22 and contact rod 35, with one Y line terminal 31 extending from the other end of coil 22, and a second line terminal 35 being connected with stationary contact-2. Line terminals 31 and 35 may extend through suitable Ainsulating bushings (not shown) provided through openings in casing I or its cover I4, and container I5 is preferably lled up to level. L with anarc extinguishing liquid, such as oil.

4 matic reclosing circuit breaker wherein time delay means, such as a dashpot is employed to obtain sufficient time delay to approximate the fuse characteristics on low currents. The diniculty in obtaining proper coordination of such `circuit breakersrand fuses'is clearly'slhown in Fig. 5, where the breaker curve RB is shown to swing away to its lower end to the right of the normal -location of the fuse curves. -tremely difficult to use a circuit breaker of this It is, therefore, ex-

"type to Vprotect a fuse link, because although it bis apparentfrom Fig. 5 that the two fuses can It will be apparent that when the current the vcircuit exceeds a predetermined Value, as on cmerloads,` solenoid coil I22 willattract .core.28.up

wardly, andjthis'upward movement of the Vcore willbe impeded :by theldashpot action of thevcore in theY cylindricalfpassage I Il, yit being `necessary thatA the fiuidj trappedv within-'f passage Il) be forcedjto escape through the relatively small clearancesbetwe'en 'core 28land' coil insulation Z5 and between thec'ore'fand contact rod E. Eventually, however, core 23 -wi-ll be drawn up` far enough Wto-f cause movement Tof the rodfupwardly, in a -manner to' be' describedLarid thus-'separate contact 4 from stationary contactvr 2 to openthe circuit.

. As soon as the circuit has beenint'errupted, solenoicl coil ZZ-willbe deenergizd and Vc'lcsingspring its contact '47' ba'ckfinto engagement vwith Vsta- -Ytionary contact 2 to;reclo"setheicircu it; Suchreclosing movement isalso delayed bythe dashpot action of core '28" in'V passage-1I 0;

s Injo'rderto! limit the' Y,number of successive A'operations of the" breaker on continuing' overloads, there isv provided a lockout tension spring 9 normallyv held-stressed betweenV a lug on cover I4 and lever- I l-bvallatchilever `I1' under the control;v ofgcountingmechanism Illi-- `Lever vI I is -vpivotedat12I on4alug dependingifrom cover I4 and has its inner end pivoted toasl'ee've 23 slidably'mounted on fthe enlarged portion '38 .of the lcontact rod. '-lheo'uterend 'of lever `I I 'extends through .a slot 25;.provid'ed :in the sideloflcasing I5, and has an operating eye 21 outside the #casing for manual ,operation .thereof C Counting mechanism .f'I 9.:has an .operatingzarm `29 adapted .Y to beactuated:byfafilange 39 :on the contact rod,

and may beofany. welleknown typecapable of,

- counting a predetermined-number.: oflclosely suc- 1 cessive breaker; operations to fftrill latchl lever I 1, such ias that fdisclosed the `copending 'application Giel-Leij. Rawlins etal.i Serial No'v513,860, liiledDecember 11;;.19fl3i0n1Circut Interrupters,

" and assienedtoethe same,ass ie neef of`this in- ;.v.enti0n.iA When levers.. l l is releaseclfl lockout spring zthen beeomesfeperative .toiholdacontact 4 at an open circuit position spaced fromqcontact 2,- -Foilowngfa-n autemateieekeut operaf tion. .the contactsfma'y bermanuallrrreciesed. by

pushing the :outer endcfleveel Il`- upwardly, ,and

e As previously Apointed out#A automatic reclosing circuit breakers are usediin circuits forthe protection of a number of fusesgwhichgmay be of diierent ratings. Figiv 5 illustrates the time- .current :characteristic :of one 1 fuse fFA; and another-.fusez'FB haring a hieherzrating-i .There is also illustrated in Fig. 5, curve RB of an auto- 75 than at lower currents, the, recloserfeurveeollld Y,be readily coordinated in that fuse FA will blow and thus protectfuse FB at all currents, the cir'- cuit breaker RB will protect fuse .FB only at low e currents, andwouldl afford no protection to this fuse at currents beyond the point where the curves intersect. It will be apparent that if the breaker could be provided with time delay means which would be less eifectiveatihigher cur-rents be made, tomore nearly simulate a fuse curve, SuCh als Curve RA. J', if. .Y :a ,3;.. The automatic reclosingWcireuiybreaker ,illus- Vvtrateol in Fig.. l is constructedto haveless ,time

delay on. higher. .overloadcurrentstd-thus more nearly approximate the time '.currentpharacteristie of fuses..ns.shown.in Fig.. .2. ithe; solenoid coil insulation .comprises at leastin, part .adashpot sleeve 2t which is. seatedgat itsA luwerendg-in an vannular recess provided injthe lowerslmplrliingV plaitelqu. alldgt. its. .1J-DEQ?! endiiengagesn .outer ange-on .a `closure:nluei 34 .toghold the-.plug .in asimilar annularrecess in the upper vs uipport- .ing plate ,zdritcontaet red-.35. hastheenlareed upper portion 3,8.-.extendinggfor a substantialidisvtance within dashpot `sleeve 12 6. when the ,breaker .contacts are at their closed circuit' position,A coil; compression spring IllY is;` lglljttvged to,t react vbetweenzthe closed lower end oi solenoid ,core 28 and theshoulcier formedbr.eplargedpettien138 ,of contactgrodf. Vl5etweengcontact rod fiifand coil spring 40, there isV positionedan actuating sleeve 42 for a purpose to be described.\, io,

s It will be observed-thattheparts areshown in 1 Fig. 2 as being. atea Yposition.v .where solenoidcore 2.8. has v l-been `drawn upwardly a i ,substantial .amount andis about `:to eauseseparetion .ot-:the

1 .breakercontacts.` A:Ascore .2,8 drawn. upwardly.

.-iteompresses spun, 40 enit-normally whenethe ,breaker opens; In .0r-cien telirisureopenins si .the

:contagia atiiaiinasleere Meis adapted@ pesi- 1 -iaeifred:36Y at a pointediaeent'.iheiupner end of core movement to positively separate the contacts. However,` a

- wardly, it also acts. afdashpotnistonfworking in. dashppi sleeve 2e se ihatemsideiane.pres- Yf siire. will berlevelened witiiin s1eeve-2-.-dependina fof. @cursa geeniheeioreeaetine ti1.is depends.;umn-.fiiiesmasnitude cette Over- Ceie zittend load current energizing ,the Yseleiizid QOiiLEi-l., In

-thiswill restore the parts to the position shown '1,111 s large @serveer-Dertien 233.10

any evenieiiwii-lfiie rieten-.theta difieren-tiel pistonis formed Within. dashpoleere 2.5m the Qnieifrecl .end-the- Smeil farsa igwerrerii n Qi. this .rpd-

f z eeerdinslv, -WhleninoverloadQfrelativelrnieh Current magnitud@ enersizes soieiieigvoilz?, .suf-

ficient oil pressure is created-witJ f'dashpot sleeve :.2 6;, as, iQ-fermes.-liirdreuiie gris/enforcing contact rod v36 upwardly because of the differential piston action, and this will occur before actuatingsleeve 42 engages the shoulder formed at enlarged portion 38 of the contact rod.

Exactly at what point in the path of travel of l.solenoid ocre 28 upwardly actual separation or" the breaker contacts occurs will, of course, depend on the magnitude of overload current flowing in the circuit. 1n any event, separation of the breaker contacts will occur earlier on high overloads than it will for low overloads, resulting in a shift to the left of the lower end of the breaker curves as at RA (Fig. 5), to a position substantially paralleling the fuse curves FA and FB.

In Fig. 3 there is illustrated another arrangement for obtaining substantially the same resulting improvement in circuit breaker time-current opening characteristic, with many of the parts illustrated here being identical with those shown in Figs. 1 and 2, and accordingly, like reference numerals are employed to designate such like parts.. In this embodiment of theinvention a contact rod 5 of uniform sizeis provided having a second pin for dening the upper limit of movement of core 28 on contact rod 6. A closure plug 44 is provided for the upper end of dashpot sleeve 2t and it has an annular recess 45 opening at the lower end of the plug and with side vent openings adjacent the upper end of the plug.

.Closure plug 4c is not held stationarily between dashpot sleeve 28 and upper supporting plate 2 i as in Fig, 2, but is .free to move relative to the dashpot sleeve and contact rod `5, being normally held at the position shown in Fig. 3 wherein a ange at the upper end of the closure plug is held seated on the upper side of supporting plate 24, by a coil compression spring engaging between plug 44. and spring retaining brackets A5?. suitably secured on the upper supporting plate 24. Here, too, solenoid core 28 is shown at an upper position just prior to the point in its path of circuit opening movement where the breaker contacts are separated. It will further be apparent that vent openings 43 of closure plug 44 are normally closed since they are covered by dashpot sleeve 25 in the position shown in Fig. 3. v

Closure plug Il!! may be forced upward against the action of spring 5u so that fluid trapped within the dashpot may escape through vent openings 48, and the amount of such venting will be dependent upon the upward force developed by solenoid coil 22 and this, oi course, is dependent on the magnitude of the overload current flowing in the circuit. On operation at relatively low overloads, the fluid pressure in dashpot sleeve 26 will not normally be sufficient to cause any upward rnc-vement of plug 44 and the circuit breaker will operate in its normal fashion, which (Fig. 5) comprises the common portion of time-current curves RA, RB. However, as the overload current increases, the4 force available for moving solenoidcore 28 upwardly also increases, thereby developing greater pressures within dashpot sleeve 2G, and closure plug 44Vwill be forced up to begin to allow some venting of the dashpot. The amount of venting, of course, will be dependent on the magnitude of the overload current, as previously pointed ou't. With such additional venting, the resistance of the dashpotto movenient of core 28 decreases so that a faster opening of. the breaker contacts results to thereby shift the lower portion of the characteristic breaker curves to the left, as at RA, to a position more nearly approximating that of the characteristic curves of fuses.

Another advantage of the structure shown in Fig, 3 is derived from thefact that when the solcnoid core 28 is drawn upwardly, the force exerted by solenoid coil 2,2 varies inversely with the distance separating core 28 andgplug 44. Thus, at lower values of overload current, the force required to startto move closure plug 44 upwardly to uncover vent openings 48 will not be reached until core 28 is substantially at the end of its circuit openingv stroke. On high currents this force will be reached at an earlier point in the upward travel of core 2S, and at very high current overloads this force may be realized substantially instantaneously so that vents 48 will be uncovered immediately.

Moreover, the length of core 23 and of closure plug i4 maybe adjusted so that core 2S Awill engage the lower end of plug 44 substantially at the same time the lower end of core 28 engages pin 35 on contact rod 6 so that the upper end oidashpot sleeve 2t will always be vented when the breaker contacts are actually separated to therebyv insure rapid separating movement of the breaker contacts.

The construction illustrated in Fig. 4 oi the drawing is likewise similar in that there is ein ployed many of the sarne parts previously illustrated, and these parts will, therefore, be designated by the same reference numerals. The solenoid core 5d 'lustrated in this embodiment ci the invention is provided with vent openings 55 at opposite sides thereof adjacent the lower end of the core. Vent openings 53 are normally adapted to be closed by a sleeve valve 58 mounted within core 54 and normally held at an upper position against stop screws S0 by a coil compression spring 52 reacting between an interior flange at the upper end of valve sleeve 53 and the lower end of core 54.

This device operates in a manner similar to the device previously described except that valve sleeve 53 is operated to move relative to solenoid core 54 in response to a predetermined high rate of acceleration of solenoid core 54, rather than by the internal pressure developed within dashpot sleeve 32 as was the case in connection with the embodiment of the invention shown in Fig. 3

of the drawing. Normally, valve sleeve 58 will not be displaced, but where solenoid core 54 is accelerated upwardly by coil 22 at a fairly high rate as by relatively high overload currents passing through the circuit, then the inertia of valve sleeve 58 will cause it to lag sufficiently behind core 54 vas to more or less uncover vent openings 56, thereby decreasing the resistance of the dashpot to movement on such high overload currents. The accelerating force which may be developed in solenoid core 54 is roughly proportional to the current flowing in the circuit, and insofar as the eiect on the recloser is concerned, this will be substantially the same as that due to the construction shown in Figs. 2 and 3. This, therefore, results in changing recloser curve RB by shifting the lower end to the left. as at RA (Fig. 5).

It will be observed that an additional function is provided due to the structure shown in Fig. 4.-, in that pin 30 is positioned to engage valve sleeve 58 in core 28, when the latter has been moved upwardly a predetermined distance to uncover vent openings 55 just before contact separation occurs. This obviously allows free venting of the dashpot arrangement substantially at the end of the circuit opening movement of solenoid core 54 so that the iinal movement thereof which is em- 'ployed to actually `separatethe" breaker contacts Will take place relatively rapidly.

There have been disclosed herein 'several mdiications Aof Vapplicants finvention vcomprising means for controlling the opening time of automatic reclosing' circuit breakers having time delay means'by using the energy stored Within the time delay device when the same is.` actuated to open the circuitso 'as to lbe effective to decrease the circuit opening 'timesat'least von high values' of overload current. In 'one embodiment of the "invention this is accomplished by a means `which and at least vsome cases'a fast rseparation of the contact is also provided 'to' thereby enhance the arc-extinguishing Haction 1 of the 'circuit' breaker.

Having describedpreferred embodiments of the invention in accordance with the-patent statutes, it is desired that this invention be not limited to these particular structures, inasmuch as it` will be apparent, particularly'to'persons skilled'inthe art, that many modications and changes may be made in these particular devices Without depart- I ing from the broad'spiritancl` scope of this'invention. t

I claim as my invention: 1. An automatic reclosing 'circuit breaker, comprising, 'separable contacts, means havingl a part movable in response-tooverloads af predetermined f distance before Tcausing separation of saidcontacts, means for# automatically reclosingsaid contacts in response toa -circuitinterrupting 'operation, means for delaying movementorI said part on atl least one -circuit interruptingeoperation; and inertia .means vyieldably-m-eunted 'on said part Vfor limited 'relative Amovement,- :soil as vrto be responsive to kpredetermined` acceleration o`f-said part, duetothe'occurrence-oran overload above a pre-determined' fvaluenor i decreasing the reinstanceof said delay means.

' 2. An automaticreclosing circuitbreaker, comprising; separable contacts," meansha-vinga part movable in response-to' Voverloads a-predetermined 'distance` beforecausingseparatien 'of'V lsaid -con- 'tacts, means for automatically-reclosing said contacts in response toA a *circuitinterrupting-operation, means for: delaying lmovementvofmsaid part jacent'the endtof its predetermined movement for also actuating said resistance decreasing means. 3. An automatic reclosing `Vcircuit'l'lbreaker, comprising separable contacts, means-having a partmovable iti-response Tto'rov'rloa'd". af predetermined 'distance befreoausing" separation "of said contacts means ff'or' automatically' reclosing saidV co tacts ingresp'o'nse to' acircuit interruptling, t'operatiomfdashpot'fmeans' for vdelaying m6ve`ment'of 'said 'part' onfat' least necircuit rupting operation, 'dashpot means for' delaying movement" of said 'part onat rleastone circuit interrupting'operatiomsaid dashpotmeans having a ventfvalv'e fmeans -normally :closing -said vent but. bei-ngv lresponsive 'to' 'pressure developed in saidfdashpotmeans by overloads'above-a lpredeterminedvalue r to 'uncover said vent, and

`means. responsive to circuit opening -movement osaid/part to'a pointadjacent therend of -its predetermined movement for 'operating ysaid valve means to uncover said vent.

`4."An automatic reclosing circ-uit breaker,

' comprising, separable contacts; means' having a part movable in response yto overloads 1 a ypredetermined distance 'before causingV separation of vsaid contacts, means for `automatically `reclosing said contacts'in response to a circuit'interinterrupting operation, themovable part of said dashpot means `having avent, 'valve fmeans 20" Ald ashpot at a'n-ormaliposition'where it is movable"\vith said movable 'part' of the dashpot yieldably supported von Tthe movable part of said means and'closes said vent, and said valve means being movable relative to said movable partl in 'response to an' acceleration of Vsaid movable part ofthe dashp'ot'means ata rate greater lthana predetermined amount, to open said vent,

5. An automatic reclosing circuit Vbreaker,

comprising; separable contacts, means having'a part movable in response to overloads-'apredetermin'ed vdistanceV before Vcausing separation` of saidcontacts, means for` automatically-remosi-ng said contacts in response toa circuit interrupting operation,'dashpot meansfor delaying movement of'said'p'art on* at least one circuit interruptingoperationfthe movable part of saidr dashpot means having a vent, 'valve means norma11y movablevvith said movable" part -of the v'-dashpot means and Aclosing 'said vent, :said valve Ymeans being movable relativetofsaidmovable `part'in responseito an acceleration' of said movable part of the dashpot'means atal rate greater than a predetermined amount to open said vent, and means responsive tov circuit"iopening` movement of said `part` of the overload-responsive r`means to a point adjacent'the end of its predetermined movement' `for also moving said valve mmeans-to open said vent.

'JAMES M. WALLACE.

` REFERENCES 1 CITED The `follovving `references are of -recordin the le of this patent:

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